1. Field of the Invention
The present invention relates to an improved short radius, low wear elbow and in particular to an elbow which has superior operating characteristics under low speed, dense conveying circumstances.
2. The Prior Art
The present invention represents an improvement in the short radius, low wear elbow described in my U.S. Pat. No. 4,387,914.
There has been a problem involved in the handling of fluent materials, such as granular or particulate particles, in making changes in direction of the flow of the fluent material. Heretofore, it has been necessary to make a turn, such as a right angle turn, in a long sweeping curve rather than a sharp turn. Generally this curve had a radius which was approximately ten times the diameter of the pipe. This long curve was necessitated by the fact that particulate material impinging upon the walls of a sharp angled turn would strike a target area directly opposite the entry port and rapidly erode the wall in this area. There were many attempts to solve this problem amongst which were the inclusion of inserts into the turn forming joint, the insert being disposable item intended to wear out. Examples of this type of elbow can be found in U.S. Pat. Nos. 1,357,259; 2,911,235; and 3,942,684.
Other attempts have been made to design an elbow configuration to accommodate the flow of fluent material through a sharp angled turn. The most interesting of these can be found in U.S. Pat. No. 2,801,133 which shows an angled nozzle having a chamber with an extension forming a pocket in axial alignment with the inlet opening. When material is blown through this nozzle, a certain quantity of material will fill the pocket and serve as a pad for the subsequently blown material. Thus, the pad of material that is formed serves as a wear surface, as in the case of the above mentioned patents.
My prior invention pertains to a short radius, low wear elbow capable of making sharp turns in fluent material handling lines without suffering from detrimental erosion characteristics of the prior art. The elbow is formed of rigid material having entrance and exit ports lying normal to each other and in close proximity, each port being surrounded by a face plate. A channel extends between the face plates making a short sharp angled turn. A cavity is formed extending from the outer tangent of the turn opposite the entrance port with the axis of the cavity lying to the outside of the axis of the entry port. The cavity joins the channel at a point one quarter of the channel diameter above the axis of the channel. Material passing through the elbow from the entrance to the exit enters the cavity in a swirling motion with the material constantly being renewed, passed on, and absorbing the blows of the subsequent material without suffering the erosive effect thereof.